1. Field of the Invention
This invention relates to a working method and apparatus, which are capable of efficiently executing such an operation as inspection, examination operations or a preventive maintenance operation in a pressure vessel of a nuclear reactor in a boiling water nuclear reactor power plant.
2. Description of Related Art
In a related art nuclear reactor, a conventional working method in a pressure vessel is described in Japanese Patent Publication (Kokai) No. 2001-281386. This conventional method is that a working apparatus is moved to accessed a reactor bottom portion after removing a fuel and control rod driving mechanism, and passing the apparatus through a reactor core portion.
A conventional apparatus and method, which makes a working apparatus access the interior of a jet pump in a pressure vessel, are described in Japanese Patent Publication (Kokai) No. 2001-159696. This conventional apparatus includes a guide mechanism, which is inserted from an upper portion of the pressure vessel and is fixed to an inlet mixer of the jet pump. The guide mechanism is used since an upper opening of the jet pump is an opening from which the interior of the jet pump is hardly seen in a vertical direction. According to this conventional method, the working apparatus is inserted into and moved to access the interior of the jet pump smoothly by using the guide mechanism.